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Classification of titanium dioxide

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Caroline Raine explores the recent discussion and considerations into the classification of titanium dioxide (TiO2) and whether it should be classified as a carcinogen.

Background

TiO2, also known as titanium (IV) oxide or titania, is the naturally occurring oxide of titanium. TiO2 is a naturally occurring mineral that is used as a pigment in paints, varnishes, plastics, sunscreens, cosmetics and even in the food industry as a colouring. It has many different uses and applications. It is so widely used because its white pigment is so bright and has a high refractive index.

Classification

TiO2 does not have a harmonised classification; it is not listed in Annex VI of the Classification, Labelling and Packaging (CLP) EC Regulation 1272/2008. Companies must make notifications of their classifications to the European Chemicals Agency (ECHA) and of those made the classifications vary tremendously from not classified to carcinogen.

The table below gives an indication on the different classifications submitted to the ECHA.

Classification

Number of submitters

Not classified

2387

Acute Tox 4 — H332

63

Acute Tox 4 — H312

4

Acute Tox 4 — H302

14

Skin Irrit 2 — H315

11

Eye Irrit 2 — H319

71

STOT SE 2 — H371

10

Resp Sens 1B — H334

1

STOT SE 3 — H335

76

STOT RE 1 — H372

69

STOT RE 2 — H373

1

Muta 2 — H341

1

Carc 1B — H350

9

Carc 2 — H351

115

Aqua Chronic 4 — H413

22

The International Agency for Research on Cancer (IARC) has classified TiO2 dust as an IARC Group 2B carcinogen, meaning it is possibly carcinogenic to humans.

In May 2016, a French proposal to the ECHA suggested that TiO2 be classified as Carc. 1B, H350i. The proposal stated that: “Available data show that TiO2 has CMR property, ie carcinogenicity that is not currently harmonised and justify a harmonised classification and labelling according to Article 36 of CLP.” The proposal can be found here.

ECHA conclusion: TiO2 proposed to be classified as suspected of causing cancer when inhaled

In June 2017, the ECHA published the long-awaited opinion on TiO2 in a press release. It proposed TiO2 to be classified as suspected of causing cancer when inhaled.

The press release stated that:

“ECHA’s Committee for Risk Assessment (RAC) concluded that the available scientific evidence meets the criteria in the CLP Regulation to classify TiO2 as a substance suspected of causing cancer through the inhalation route. The opinion will be formally adopted later by written procedure or at the September meeting.

“The Committee assessed the carcinogenic potential of TiO2 against the criteria in the CLP Regulation and, having considered the available scientific data, concluded that it meets the criteria to be classified as suspected of causing cancer (Category 2, through the inhalation route).

“The Committee also concluded that there was insufficient evidence to classify TiO2 in the more severe category for carcinogenicity (Category 1B) as was originally proposed by the dossier submitter, France. This more severe category refers to a substance which is presumed to cause cancer.”

Classification of TiO2 published

Then in October 2017, ECHA’s Committee for Risk Assessment (RAC) published its scientific opinion to classify TiO2 as a suspected carcinogen (Category 2) by inhalation.

The classification of TiO2 has been discussed for many months (since March 2017). ECHA’s RAC concluded that “the available scientific evidence meets the criteria in the CLP Regulation to classify TiO2 as a substance suspected of causing cancer through the inhalation route”. This means that it meets the criteria to be classified as suspected of causing cancer (Category 2, through the inhalation route).

The Committee concluded that there was insufficient evidence to classify TiO2 in the more severe category for carcinogenicity (Category 1B) as was originally proposed by the dossier submitter, France.

Robert Bird of the Titanium Dioxide Manufacturers Association (TDMA) noted his disappointment, stating that “the scientific evidence is clear; there are no grounds for classifying TiO2 as a Category 2 carcinogen”. He went on to note that “classification would do nothing to increase the level of protection of human health and the environment”, an important point considering the reasons for classification and labelling.

2018 substance evaluation — CoRAP

Then, in 2018, TiO2 was added to the Community Rolling Action Plan (CoRAP). If a substance is on this list, it means that a Member State has evaluated or will evaluate it over the coming years.

TiO2’s safety as a food additive reaffirmed

The European Food Safety Authority (EFSA) reaffirmed on 29 June 2018 the safety of TiO2 as a food additive (E171), following a request on 22 March 2018 from the European Commission for a scientific opinion.

The TDMA calls for EFSA’s opinion to be respected and for EU legislation on food safety to be observed throughout the EU.

TDMA stated: “E171 is the most effective white colourant in use and it has gone through rigorous European testing and classification which has continually demonstrated its safety. EFSA established in 2016 that data on E171 showed no health concerns for consumers and EFSA’s new opinion supports this conclusion. The opinion sends a clear signal that the current discussion in France regarding the suspension of placing E171 and food containing it on the market is unwarranted. In view of this, the TDMA calls on the European Commission to ensure that the EU’s food safety legislation is followed throughout the Union.”

Classify all TiO2 forms as suspected carcinogens

In July 2018, a group of NGOs called on EU Member States to support the full implementation of ECHA's RAC opinion for the classification of all forms of TiO2 as a Category 2 carcinogen.

Conclusions

Despite the ECHA announcing a new classification, we have yet to see this formally published within CLP. There are conflicting opinions about the classification of TiO2 and we wait with anticipation as to the outcome of future discussions.